An electric power converter is mounted in an electric vehicle or a hybrid vehicle, etc., for converting DC power from a battery into three-phase AC power in order to drive a three-phase AC rotating electric machine. Such an electric power converter is disclosed in Japanese Patent Application Laid-Open Publication No. 2011-171449 (JP-A-2011-171449), for example.
The electric power converter of JP-A-2011-171449 has semiconductor modules, a cooler for cooling the semiconductor modules, and a case for enclosing the semiconductor modules and the coolers. The cooler has a refrigerant passage for circulating a refrigerant therein, and is formed by connecting a plurality of cooling tubes that are stacked alternately with the semiconductor modules by connecting tubes. The cooler has a supply pipe for supplying the refrigerant to the refrigerant passage, and a discharge pipe for discharging the refrigerant in the refrigerant passage. The supply pipe and the discharge pipe are inserted and disposed respectively on a pair of sealing members that fill gaps between the case and the tubes.
The case has a case body with a bottom portion disposed below the semiconductor modules and the cooler and wall portions disposed standing perpendicularly from outer edges of the bottom portion, and a lid portion that covers an opening formed on an upper end of the case body. Cutouts for projecting the supply pipe and the discharge pipe of the cooler to the outside of the case are formed on one of the wall portions. The case body, the lid portion, and gaps between the supply pipe and the discharge pipe are sealed by sealing members by fitting the sealing members to which the supply pipe and the discharge pipe are inserted into the cutouts as well as fixing the lid to the case body.
However, the electric power converter disclosed in JP-A-2011-171449 has the following problems.
In the electric power converter disclosed in JP-A-2011-171449, the case body, the lid portion and the supply pipe or the discharge pipe are sealed by a single sealing member. Therefore, when misalignment between the case body and the lid portion, and misalignment between the case and the supply pipe or the discharge pipe occur one-sidedly, the gap increases partially. In such a case, the gap increases with respect to the size of the sealing member, and it becomes difficult to maintain the sealability by the sealing member.
Further, when load is applied to tips of the supply pipe and the discharge pipe in a direction intersecting with an axial direction of the pipe, the sealing member is easily deformed by being pressed by the supply pipe and the discharge pipe. Thus, it is not possible to suppress the deformation of the supply pipe and the discharge pipe by the sealing member, and stress is generated at roots of the supply pipe and the discharge pipe. Therefore, it is necessary to provide a clamp for regulating the displacement of the supply pipe and the discharge pipe, and thus the number of components of the electric power converter has been increased.
In addition, a miniaturization of the electric power converter is desired in recent years. As a means to reduce the size of the electric power converter, there is a miniaturization of the cooler. The miniaturization of the cooler is carried out by a miniaturization of an outer profile of the cooling tube, and a miniaturization of a diameter of the connecting pipe. At this time, it is necessary to reduce diameters of the supply pipe and the discharge pipe to fit the outer profile of the cooling tube. On the other hand, since a diameter of an external pipe connected to distal ends of the supply pipe and the discharge pipe is the same as a diameter of the conventionally used pipe, it is necessary to form small diameter portions and large diameter portions having diameters larger than the small diameter portions in the supply pipe and the discharge pipe. When disposing the small diameter portions and the large diameter portions in the supply pipe and the discharge pipe, since changing sections for changing the diameters between the two are required, it is necessary to increase the length of the supply pipe and the discharge pipe.